1. Field of the Invention
The invention is in the technical field of the crop protection agents which can be used against harmful plants, for example in crop plants, and which, as active compounds in the herbicidal compositions, comprise a combination of aclonifen and a further herbicide.
2. Description of Related Art
The herbicidally active compound aclonifen (manufacturer: Bayer CropScience) belongs to the group of the diphenyl ethers, and mixtures of this group with other herbicides are known from the literature: for example (e.g.) U.S. Pat. No. 4,394,159 A, EP 0007482 A. U.S. Pat. No. 5,858,920 B describes, inter alia, heteroaryloxyacetamides in mixture with individual active compounds such as, for example, the herbicide aclonifen; however, without any experimental data for the synergistic effect.
The herbicidal active compound aclonifen is characterized by a broad activity against mono- and dicotyledonous harmful plants and is employed, for example, predominantly by the pre-emergence method in sown and/or planted agricultural or horticultural crop plants and also on non-crop land (for example in cereals such as wheat, barley, rye, oats, triticale, rice, corn, millet, sugar beet, sugar cane, oilseed rape, cotton, sunflowers, soybeans, potatoes, tomatoes, beans, flax, pasture grass, fruit plantations, plantation crops, greens and lawns and also squares of residential areas or industrial sites, rail tracks).
As individual active compound, aclonifen is commercially available, for example, under the trade names Challenge®, Bandur®, Fenix® and Prodigio®. In addition to the use of the individual compound, mixtures of aclonifen with other herbicides are also known from the literature (e.g. AU 635599 B, AU 642986 B, AU 641500 B, AU 659028 B, AU 663028 B, AU 712501 B, U.S. Pat. No. 6,046,133 B, EP 0958742 A) and commercially available: mixtures with amitrole (e.g. Derby®, Illico TL Express®, Muleta®), with isoxaflutole (e.g. Acajou®, Lagon®, Merlin Combi®), with alachlor (e.g. Manager®), with flurtamone (e.g. Nikeyl®), with oxadiargyl (e.g. Opalo®, Carioca®) and with oxadiazon (e.g. Phare®, Cline®).
In spite of the good activity of aclonifen as individual active compound and in the mixtures already known, there is still a need for improving the application profile of this active compound in specific areas of use. There are various reasons for this, such as, for example, further increase of efficacy in specific areas of application and in connection with different soil properties and irrigation conditions, enhancement of crop plant compatibility, as a reaction to novel production techniques in individual crops and/or to the increasing occurrence of herbicide-resistant harmful plants (e.g. in cereals, rice and corn, but also in potatoes, sunflowers, peas, carrots and fennel), for example with target-site resistance (e.g. TSR (abbreviation: TSR; where the weed populations comprise biotypes having a target-site-specific resistance, i.e. the binding site at the site of action is modified as a result of natural mutations in the gene sequence so that the active compounds are no longer able to bind, or bind in an unsatisfactory manner, and are therefore no longer able to act) and enhanced metabolic resistance (abbreviation: EMR; where the weed populations comprise biotypes having a metabolic resistance, i.e. the plants are capable of metabolizing the active compounds more quickly via enzyme complexes, that means the active compounds are degraded more rapidly in the plant). According to the Herbicide Resistance Action Committee (abbreviation: HRAC; a committee of the research-conducting industries), resistances to approved active compounds are classified according to their mode of action (MoA): e.g. HRAC group A=acetylcoenzyme-A carboxylase inhibitors (MoA: ACCase) or HRAC group B=acetolactate synthase inhibitors (MoA: ALS). These improvements of the application profile may be of importance both individually and in combination with one another.
One way of improving the application profile of a herbicide may be to combine the active compound with one or more other suitable active compounds. However, in the combined application of a plurality of active compounds, there are frequently phenomena of chemical, physical and biological incompatibility, for example lack of stability of a coformulation, decomposition of an active compound and/or antagonism of the active compounds. What is desired, however, are combinations of active compounds having a favorable activity profile, high stability and ideally a synergistically enhanced activity which allows the application rate to be reduced compared to the individual application of the active compounds to be combined. Likewise, desirable are combinations of active compounds which increase crop plant compatibility in general and/or can be used for specific production techniques. These include, for example, a reduction of sowing depth which, for crop compatibility reasons, can frequently not be used. In this manner, in general a more rapid emergence of the crop is achieved, their risk of emergence diseases (such as, for example, Pythium and Rhizoctonia) is reduced, and winter survival and stocking are improved. This also applies to late sowing which would otherwise not be possible owing to the crop compatibility risk.